Answer:
I can be quick and then I'm deadly, I am a rock, shell and bone medley. If I was made into a man, I'd make people dream, I gather in my millions By ocean, sea and stream.
I go around in circles, but always straight ahead. Never complain, no matter where I am led.
I turn around once. What is out will not get in. I turn around again. What is in will not get out.
I am a good state, there can be no doubt of itΝΎ But those who are in, entirely are out of it.
You heart it speak, for it has a hard tongue. But it cannot breathe, for it has not a lung.
I have two bodies joined together as one. When standing still I run and run.